Problems with Design Days

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Hello all,

Has anyone had trouble with erroneous "HOURS ANY ZONE ABOVE COOLING THROTTLING RANGE" when using cooling design days? This number reported in both the BEPS and BEPU reports does not offer any insight on where it comes from, so it's especially difficult to troubleshoot.

I'm noticing several different simulation runs where the "PERCENT OF HOURS ANY SYSTEM ZONE OUTSIDE OF THROTTLING RANGE" is at either 0 or 0.01% while there are thousands of "HOURS ANY ZONE ABOVE COOLING THROTTLING RANGE." I thought when this field was added that it was supposed to report unmet hours, but I can't see why the numbers don't agree.

It appears that eQUEST has a hard time distributing airflow to zones correctly unless enough days are included in the "design day" dialogue box, but when you enter too many, the phenomenon above tends to occur.

Can anyone shed light on where the "HOURS ANY ZONE ABOVE COOLING THROTTLING RANGE" and "HOURS ANY ZONE BELOW HEATING THROTTLING RANGE" come from since LEED reviewers are now looking at this and only this to determine unmet hour compliance?

Thanks,

Matt Edwards, P.E., LEED AP BD+C

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Thanks Rut. I only have two "design day" components in the model. The trouble is with how many days you allow them to run for. It's the bottom field on the lower left hand side of the design day dialogue box with BDL keyword NUMBER-OF-DAYS. The simulation behaves very oddly when you modulate this number, and to this point my conclusion is there is trouble within eQUEST with accurately allotting airflow to zones as required based on their "design day" calculated load. I haven't figured out exactly what the problem is. The building in question has an odd footprint shape with lots of glass, so I'm betting the problem is with how eQUEST calculates solar load and provides for zone airflow in response.

My issue with the way LEED unmet hours are reported/reviewed is that the fields in BEPS/BEPU do not provide any information troubleshoot them. In previous versions of eQUEST (DOE-2.2-47d and before) there were no heating and cooling fields, so you either had to use the PERCENT OF HOURS ANY SYSTEM ZONE OUTSIDE OF THROTTLING RANGE which didn't break them up into heating and cooling or use the SS-R reports.

I often find under eQUEST v3.64 that the SS-R reports show no unmet hours anywhere, but there are still some showing up in the BEPS/BEPU reports under HOURS ANY ZONE ABOVE COOLING THROTTLING RANGE and HOURS ANY ZONE BELOW HEATING THROTTLING RANGE. I'm suspicious of them since during the same run the PERCENT OF HOURS ANY SYSTEM ZONE OUTSIDE OF THROTTLING RANGE lists 0 or a very small percentage (0.05% or lower). How can the two not agree?

As far as my comments, apologies if you're a LEED reviewer. If you are, you have a tough job, and there is a lot of information to pour over to determine if a model is done correctly. Appendix G is still very ambiguous since it grew out of the pre-LEED days and is meant to appease many software packages. It would be nice to have more specific information about how passages in Appendix G are interpreted, and perhaps a revamp would be appropriate since the energy modeling world has gone through seismic change in the last 5 years.

Thanks for the response.

Matt Edwards, P.E., LEED AP BD+C

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Joined: 2012-11-12
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